Triglycerides comprise linear combinations of aliphatic chains covalently attached to a glycerol backbone. Triglycerides serve as vital sources of cellular energy and caloric potential in living organisms. Recent work has provided unambiguous evidence of the importance of total triglycerides as a lipid class to the development of heart disease, stroke, obesity and diabetes in humans all of which are life taking diseases which take a staggering toll of human lives each year. Additionally, such afflictions destroy or significantly reduce the quality of life even if not immediately fatal.
Triglycerides (TG) includes molecules of glycerol esterified with three fatty acids. TG have a glycerol backbone structure while the associated fatty acids are predominately unsaturated. Dihydroxyacetone phosphate (DHAP) or glycerophosphate produced during glycolysis is the precursor for triacylglycerol synthesis (Triacylglycerides are triglycerides) in mammalian cells including adipocytes and hepatocytes.
In mammals, complex and diverse mechanisms have evolved to regulate the TG content in serum, the delivery of fatty acids derived from serum TG molecular species to cells (e.g., lipoprotein lipase and fatty acid transport protein), and the intracellular storage of fatty acids by esterification to a glycerol backbone for subsequent storage as TG molecular species. It is highly desired to be able to readily determine the identity of TG molecular species along with their respective quantity present in biological samples including living mammalian and plant samples. In many such areas of research and medical therapy it is desired and necessary to analyze large and increasing numbers of biological samples in an enhanced fashion such as those samples comprising TG molecular species.
For at least the aforegoing reasons biological analytical methods which readily and directly identify and quantify TG molecular species in biological samples will be an integral and vital part of research which produces discoveries of benefit to mankind in the biochemistry of plants and animals dealing with coronary artery disease, stroke, atherosclerosis and obesity. Accordingly an enhanced analysis of such biological samples is needed which provides a TG molecular species profile.
The TG molecular species profile reflects the nutritional and metabolic history of each cell as well as its anticipated energy storage requirements. Alterations in TG molecular species synthesis and catabolism have been demonstrated to play prominent roles in obesity, atherosclerosis, insulin release from pancreatic β cells, and alcohol-induced hepatic dysfunction (1-7). Moreover, recent studies have identified the importance of alterations in intracellular triglycerides as a potential mediator of diabetic cardiomyopathy (5,8).
Although some studies have measured total TG molecular species content in multiple different disease states, a paucity of information on TG molecular species changes during pathophysiological alterations is available. The first detailed molecular species analyses of TG in diabetic rat myocardium demonstrated a dramatic alteration in TG molecular species composition without substantial changes in TG mass (8). Accordingly, it seems likely that changes in TG molecular species composition also contributes to the pathophysiological sequelae of other disease states.
Previous attempts at direct TG quantitation by positive-ion electrospray ionization mass spectrometry (ESI/MS) were undesirably confounded by the presence of overlapping peaks from choline glycerophospholipids requiring chromatographic separation of lipid extracts prior to ESI/MS analyses. Thus it is highly desired to have an enhanced method and system for determining TG content in various living mammalian and plant cellular systems which obviates the chromatographic separation process requirement. Moreover, isobaric molecular species present in all biological tissues prevent determination of individual molecular species of triglycerides from molecular weight determinations alone.